CN107154528B

CN107154528B - Single radiator-based compact single-layer planar structure tri-polarization MIMO antenna

Info

Publication number: CN107154528B
Application number: CN201710245241.6A
Authority: CN
Inventors: 朴大志; 王亚金
Original assignee: Communication University of China
Current assignee: Communication University of China
Priority date: 2017-04-14
Filing date: 2017-04-14
Publication date: 2020-04-07
Anticipated expiration: 2037-04-14
Also published as: CN107154528A

Abstract

A compact single-layer planar structure tripolar MIMO antenna based on a single radiator belongs to the antenna field of communication technology. Using the same radiator, that is, a patch antenna, excitation at different positions of the metal patch can achieve three mutually orthogonal radiation modes at the same resonant frequency on the same radiator; these three radiation modes have positive Two magnetic dipoles and one electric dipole in the cross-direction diagram can obtain two mutually orthogonal horizontally polarized electric fields and one vertically polarized electric field to form a three-polarized antenna; in order to make the three poles The modified antenna works in the same frequency band, and a certain number of metal vias are added between the metal patch and the grounded metal plate to reduce the resonance frequency of the vertical electric field polarization mode and increase the resonance frequency of the horizontal electric field polarization mode. make it work in the same frequency band.

Description

Single radiator-based compact single-layer planar structure tri-polarization MIMO antenna

Technical Field

The invention relates to a compact single-layer plane structure triple-polarization MIMO antenna based on a single radiator, and belongs to the field of antennas of communication technologies.

Background

As is well known, an electromagnetic field is a vector field, and therefore, in order to make full use of its vector characteristics, it is necessary to develop a vector antenna, or multi-polarization antenna, capable of simultaneously responding to a plurality of polarization states. The antenna can more fully utilize the vector information of the electromagnetic field, and has important application prospects in systems of communication, positioning, navigation, target identification, imaging and the like. In a wireless communication system, Multiple-Input Multiple-Output (MIMO) technology is used, Multiple antennas are simultaneously used at a transmitting end and a receiving end, and space-time signal processing technology is combined to improve the spectrum efficiency and channel capacity of the communication system by multiples, so the MIMO technology becomes a core technology in wireless communication systems such as 802.11n, 802.16, LTE, 5G and the like. In a conventional MIMO system based on single-polarized antennas, in order to obtain a sufficiently large spatial degree of freedom, the spacing between antenna elements in the transmitting array and the receiving array is required to be sufficiently large. If a single-polarized antenna array is used, the minimum array element spacing required in a multipath rich environment is half a wavelength, while in a multipath sparse environment, 5-10 wavelengths may be achieved. Because the space size of the base station and the mobile user terminal is limited, the single-polarization MIMO system is greatly limited in practical application, and the MIMO system based on multi-polarization antenna can solve the problem well.

In an electromagnetic field, at most 3 orthogonal electric field components and 3 orthogonal magnetic field components exist at any point in space, and theoretical research shows that in a channel rich in scattering, the degree of freedom of a MIMO system formed by vector antennas which are orthogonal at the same point can be obtained to be at most 6. Thus, a multi-polarized antenna can be realized by a combination of various antennas having electric dipole radiation characteristics and magnetic dipole radiation characteristics. Because it is difficult to realize the common-point orthogonal, low-coupling and compact multi-polarization antenna, the existing multi-polarization antenna such as the two-polarization and the three-polarization antenna mostly adopts electric dipoles and magnetic dipoles which are respectively designed by radiation units, and is realized by a three-dimensional structure or a multilayer structure. For example, in application 201380002320.4, a triple polarized antenna is implemented by a multilayer structure, using a rectangular patch to implement two polarizations in the horizontal direction, and then using a short circuit boundary condition, a coaxial line is loaded through the center of the patch with a single disk to implement polarization in the vertical direction. In application 201610064872.3, a tri-polarized antenna with spatial and polarization diversity is proposed, but this antenna is a more complex spatial structure. Because the transverse and longitudinal dimensions of the antenna are relatively large in the multi-polarization antenna design realized by the multilayer or three-dimensional structure, the antenna is not beneficial to integration and application in portable equipment, and with the development of technologies such as the internet of things technology, the dense cellular network technology and the large-scale MIMO antenna array, the requirements of compactness, miniaturization, portability and the like are provided for the antenna design.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a compact single-layer plane structure tri-polarization MIMO antenna based on a single radiator by utilizing the polarization diversity principle, and the three polarization radiation modes comprise two equivalent magnetic dipoles and one equivalent electric dipole with orthogonal directional patterns.

A compact single-layer plane structure triple-polarization MIMO antenna based on a single radiator utilizes the same radiator, namely a patch antenna, to excite at different positions of a metal patch, so as to realize that three mutually orthogonal radiation modes under the same resonant frequency are obtained on the same radiator; the three radiation modes are two magnetic dipoles and an electric dipole with orthogonal directional diagrams, two horizontal polarized electric fields and a vertical polarized electric field which are orthogonal to each other can be obtained, and a triple polarized antenna is formed; in order to enable the three polarized antennas to work in the same frequency band, a certain number of metal through holes are added between the metal patch and the grounding metal plate, so that the resonant frequency of the vertical electric field polarization mode is reduced, and the resonant frequency of the horizontal electric field polarization mode is improved, and the effect of working in the same frequency band is achieved.

Exciting two orthogonal polarization modes of the microstrip patch antenna by utilizing coaxial line feed at the first port and the second port, wherein TM11 is equivalent to two magnetic dipoles orthogonally arranged along the horizontal direction in radiation characteristic; the third port also utilizes coaxial line feeding, and realizes a similar monopole antenna radiation mode under the same frequency band, namely a TM02 mode of a monopole patch antenna, by adding a metal through hole, wherein the radiation characteristic is equivalent to an electric dipole placed along the vertical direction.

When the first port and the second port feed power respectively, the directions of electric fields on the patches are parallel to the floor and are orthogonal to each other; when the third port feeds power, the direction of the electric field is vertical to the floor.

The antenna comprises a grounding metal plate, a dielectric substrate, a radiating metal patch, a plurality of metal through holes and three coaxial line feed ports; the radiating metal patch can be circular, and the feeding mode of three ports can also adopt aperture coupling feeding and microstrip line feeding.

The invention has the advantages that:

the invention provides a single radiator-based compact single-layer planar structure tri-polarization MIMO antenna for the first time. The three-polarization antenna with the three common-point orthorhombic and orthogonal directional diagrams is realized by utilizing the same radiator and obtaining two orthogonal horizontal polarization electric fields and one orthogonal vertical polarization electric field component with the two orthogonal horizontal polarization electric fields through different excitation point positions, three polarizations work in the same frequency band, resonance frequencies coincide, the antenna structure is a single-layer plane structure, and the three-polarization antenna is simple and compact in structure and easy to process and realize.

In the invention, the equivalent capacitance and the equivalent inductance between the metal patch and the floor are changed by adding the metal via hole, so that the resonant frequency of the vertically polarized monopole antenna is reduced, the resonant frequency of the horizontally polarized microstrip antenna is improved, and the vertically polarized mode can work in the same frequency band as two horizontally polarized modes excited by the second port of the first port.

The same metal patch structure is used as a radiating body, a certain number of metal via holes are added to connect the metal patch with the grounding metal plate, and the metal patch is excited at different positions by utilizing a cavity mode theory, so that three mutually orthogonal radiation modes under the same resonant frequency are obtained by the same radiating body. The three radiation modes have orthogonal patterns. Using a coaxial line feed at the first horizontally polarized port 10, whose radiation characteristics can be equated to a magnetic dipole placed in the X-direction, the patch antenna will operate in TM11 mode. When the second horizontally polarized port 12 is also fed by a coaxial line, its radiation characteristic may be equivalent to a magnetic dipole placed in the Y direction, and the patch antenna will operate in TM11 mode. The third port 11 of the patch center feed is excited to generate vertical polarization electromagnetic wave along the Z axis, which is based on a patch antenna added with a short-circuit metal via hole, and the radiation pattern of the patch antenna is similar to a monopole antenna by using the cavity mode theory, which is equivalent to an electric dipole vertically arranged along the Z axis. The antenna with the structure can obtain three mutually orthogonal electric field components which work in the same frequency band.

Drawings

A more complete and thorough understanding of the present invention, and many of the attendant advantages thereof, will be readily obtained by reference to the following detailed description when considered in connection with the accompanying drawings, which are set forth to provide a further understanding of the invention and form a part hereof, and to illustrate exemplary embodiments thereof and, therefore, not limit the invention, as the following figures:

fig. 1 is a top view of a compact single-layer planar tri-polarization MIMO antenna based on a single radiator.

Fig. 2 is a side view of fig. 1.

Fig. 3 is a simulation result of return loss, i.e., a circuit parameter S, of the triple-polarized antenna in the embodiment of the present invention.

Fig. 4(a) shows one of the XZ plane and YZ plane radiation patterns when the first feeding port 10 of the triple polarized antenna is excited in the embodiment of the present invention.

Fig. 4(b) shows the second XZ-plane and YZ-plane radiation patterns when the first feed port 10 of the triple-polarized antenna according to the embodiment of the present invention is excited.

Fig. 5(a), one of the XZ plane and YZ plane radiation patterns when the triple polarized antenna in the embodiment of the present invention is excited at the second feeding port 12.

Fig. 5(b) shows the second XZ plane and YZ plane radiation patterns when the second feeding port 12 of the triple-polarized antenna in the embodiment of the present invention is excited.

Fig. 6(a) shows one of the XZ plane and YZ plane radiation patterns when the third feeding port 11 of the triple-polarized antenna in the embodiment of the present invention is excited.

Fig. 6(b) shows the second XZ plane and YZ plane radiation patterns when the third feeding port 11 of the triple-polarized antenna in the embodiment of the present invention is excited.

Detailed Description

It will be apparent that those skilled in the art can make many modifications and variations based on the spirit of the present invention.

As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element, component or section is referred to as being "connected" to another element, component or section, it can be directly connected to the other element or section or intervening elements or sections may also be present. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Example 1: a compact single-layer plane structure three-polarization MIMO antenna based on a single radiator is composed of a circular metal patch, a dielectric substrate, a metal floor and a plurality of metal through holes penetrating through the dielectric substrate and connecting the metal floor and the metal patch.

According to the cavity mode theory, excitation is carried out at different positions of the metal patch, a triple-polarized antenna consisting of two equivalent magnetic dipoles and one equivalent electric dipole with orthogonal directional patterns is realized, and the antenna forms three orthogonal polarized radiation modes under the same working frequency band.

When the first horizontal polarization port and the second horizontal polarization port utilize coaxial line feeding, an internal field is solved by a mode expansion method according to boundary conditions, an antenna radiation field is obtained by radiation of equivalent magnetic current of gaps around a cavity, two orthogonal horizontal direction electric fields can be obtained, the polarization modes are TM11 and are orthogonal to each other.

The third port excites an electric field in the vertical direction by using coaxial line feeding, similar to the radiation characteristic of a monopole antenna, and works in a TM02 mode of the monopole patch antenna, and the three modes work in the same frequency band, so that a triple polarized antenna is obtained. According to the invention, by adding the metal via holes and adjusting the distance and the number of the metal via holes, the equivalent capacitance and the equivalent inductance between the metal patch and the floor are changed, so that the resonant frequency of the vertically polarized monopole antenna is reduced, the resonant frequency of the horizontally polarized microstrip patch antenna is improved, and the three polarizations can work in the same frequency band through optimization.

Example 2: a single radiator-based compact single-layer planar structure triple-polarized MIMO antenna is characterized in that a dielectric substrate adopts an epoxy resin plate Fr4 with the dielectric constant of 4.4, a feeding port adopts coaxial line feeding with the characteristic impedance of 50 ohms, and the structure of the single radiator-based compact single-layer planar structure triple-polarized MIMO antenna is shown in figures 1 and 2.

Referring to fig. 1 and 2, a compact single-layer planar structure triple-polarized MIMO antenna based on a single radiator is composed of a grounded metal plate 1, a dielectric substrate 2 with the same area size, a

circular metal patch

3, 12 metal vias 4 penetrating through the dielectric substrate and connecting the grounded metal plate and the circular metal patch, and a first feed port 10, a third feed port 11 and a second feed port 12 of three coaxial line feed structures;

one side of the grounding metal plate 1 is connected with the medium substrate 2, one side of the medium substrate 2 is connected with the circular metal patch 3, the metal via holes 4 penetrate through the grounding metal plate 1, the medium substrate 2 and the circular metal patch 3, the metal via holes 4 are uniformly distributed on the end face of the circular metal patch 3, and the number of the metal via holes 4 is 12; the first feed port 10, the third feed port 11 and the second feed port 12 penetrate through the grounding metal plate 1, the dielectric substrate 2 and the circular metal patch 3, the third feed port 11 is located at the center of the circular metal patch 3, the first feed port 10 and the second feed port 12 are distributed at the edge of the circular metal patch 3, and the first feed port 10 and the second feed port 12 are 90 degrees apart from each other by taking the circular metal patch 3 as the center.

12 metal via holes 4 are symmetrically arranged on the end face around the center, the included angle between every two metal via holes 4 is 30 degrees, the distance from every two metal via holes 4 to the center of the patch is equal, and the radiuses of all the metal via holes 4 are the same.

When the first feed port 10 and the second feed port 12 are excited, the radiation is equivalent to two orthogonal magnetic dipole antennas, two electric fields polarized along the Y and X directions can be obtained, and when the third feed port 11 is excited, the radiation is equivalent to an electric dipole, and a third electric field polarized along the Z direction can be obtained.

The 12 metal through holes are symmetrically arranged on the XY plane around the Z axis, the included angle between every two through holes is 30 degrees, the distance between every two through holes and the center of the patch is equal, and the radiuses of all the metal through holes are the same. The height of the metal via is the thickness of the dielectric substrate.

The first horizontally polarized port 10, when fed, radiates with a radiation characteristic equivalent to a magnetic dipole placed along the X-axis in the horizontal direction, radiating an electric field polarized along the Y-axis. The second vertically polarized port 12, when fed, acts as a magnetic dipole placed along the Y-axis, radiating an electric field polarized along the X-axis. The third port 11, which is fed at the center of the patch, is excited to generate a vertically polarized electromagnetic wave along the Z-axis, corresponding to an electric dipole placed along the Z-axis.

The simulation result of the return loss of the patch-based compact single-layer planar triple-polarization MIMO antenna shown in fig. 3 shows that the three polarized resonant frequency bands coincide, the bandwidth of the middle patch monopole antenna is 3.74-3.98GHz (240MHz), and the bandwidth of the two microstrip antennas is 3.84-3.96GHz (120 MHz).

Fig. 4(a), 4(b), 5(a), and 5(b) show the XZ-plane radiation pattern and YZ-plane radiation pattern of the patch-based compact single-layer planar structure of the tri-polarized MIMO antenna operating at 3.86GHz when the first feed port 10 and the second feed port 12 are excited, respectively, which are equivalent to two orthogonally disposed magnetic dipoles, and two horizontally polarized electric fields can be obtained. The first polarization direction is along the Y-axis and the second polarization direction is along the X-axis.

Fig. 6(a) and 6(b) show the XZ plane radiation pattern and the YZ plane radiation pattern when the patch-based compact single-layer planar triple-polarized MIMO antenna is excited at 3.86GHz at the third feeding port 11, respectively, and it can be seen that the radiation pattern corresponds to an electric dipole placed along the Z axis.

As described above, although the embodiments of the present invention have been described in detail, it will be apparent to those skilled in the art that many modifications are possible without substantially departing from the spirit and scope of the present invention. Therefore, such modifications are also all included in the scope of protection of the present invention.

Claims

1. A compact single-layer planar structure three-polarized MIMO antenna based on a single radiator, characterized in that using the same radiator, that is, a patch antenna, excitation at different positions of the metal patch is realized on the same radiator Obtain three mutually orthogonal radiation modes at the same resonant frequency; these three radiation modes are two magnetic dipoles and one electric dipole with orthogonal patterns, and two mutually orthogonal levels can be obtained A polarized electric field and a vertically polarized electric field form a three-polarized antenna; in order to make the three polarized antennas work in the same frequency band, a certain number of metal vias are added between the metal patch and the grounded metal plate , the resonant frequency of the vertical electric field polarization mode is reduced, and the resonance frequency of the horizontal electric field polarization mode is increased, so that it can work in the same frequency band; one side of the grounded metal plate is connected to the dielectric substrate, and one side of the dielectric substrate is connected to the circular Metal patch, metal vias run through the grounding metal plate, dielectric substrate and circular metal patch, and metal vias are evenly distributed on the end face of the circular metal patch; the first feeding port, the third feeding port and the second feeding port The feeding port runs through the ground metal plate, the dielectric substrate and the circular metal patch, the third feeding port is located in the center of the circular metal patch, and the first feeding port and the second feeding port are distributed on the circular metal patch The edge of the first feeding port and the second feeding port are separated by 90 degrees with the circular metal patch as the center.

2. A compact single-layer planar structure tri-polarized MIMO antenna based on a single radiator according to claim 1, characterized in that the first port and the second port are fed with coaxial lines to excite the microstrip patch The two orthogonal polarization modes of the chip antenna, TM11, the radiation characteristics are equivalent to two magnetic dipoles placed orthogonally in the horizontal direction; the third port is also fed by coaxial wire, which is realized by adding metal vias The radiation pattern of a similar monopole antenna in the same frequency band, that is, the TM02 pattern of the monopole patch antenna, is equivalent to an electric dipole placed in the vertical direction.

3. A compact single-layer planar structure three-polarized MIMO antenna based on a single radiator according to claim 1, characterized in that when the first port and the second port are respectively fed, the direction of the electric field on the patch is parallel On the floor and orthogonal to each other; when the third port is fed, the direction of the electric field is perpendicular to the floor.

4. A compact single-layer planar structure three-polarized MIMO antenna based on a single radiator according to claim 1, characterized in that the antenna comprises a grounded metal plate, a dielectric substrate, a radiating metal patch, several Metal vias, three coaxial feed ports; the radiating metal patch can be circular, and the feed mode of the three ports can also use aperture coupling feed or microstrip line feed.

5. The compact single-layer planar structure tri-polarized MIMO antenna based on a single radiator according to claim 1, characterized in that there are 12 metal vias.

6. A compact single-layer planar structure tripolar MIMO antenna based on a single radiator according to claim 2, characterized in that the metal vias are placed symmetrically on the end face around the center, and the included angle between each metal via is 30 degrees, each metal via is the same distance from the center of the patch, and all metal vias have the same radius.